ORIGINS of the HepaRG cell line

Christiane Guguen-Guillouzo, head of the 522 unit of the French National Institute of Health and Medical Research (INSERM) from 1997 to 2008 recalls:

"We took our chances and we made the most of all the opportunities that came along!

We had already undertaken hundreds of assays with several other groups to select cell lines with highly relevant biological or metabolic features. We knew it was therefore highly risky to keep trying."

"In the eighties and nineties, Rennes University team was one of the world leading groups within the scientific community working on human hepatocytes primary cultures. As we were extremely concerned by the painful troubles caused by hepatitis infectious diseases and we were aiming at taking advantage of our successful human differentiated primary cultures, we started to challenge a possible in vitro infection mechanism of human primary cultures by hepatitis viruses.

Philippe Gripon, a young PhD, rapidly succeeded in infecting mature human hepatocytes with high efficiency, using sera from HBV infected patients. The results published in 1993, were extremely convincing…fortunately. However, it became immediately clear that there were huge problems with HCV infections. We therefore postulated that we could benefit from hepatic cells already infected by the HCV virus obtained from patients (in vivo) once they were plated in culture…a naïve hypothesis indeed, but very positive for the opportunities which came along!

At this point, we thought we would hold more chances by combining the experience and efforts of the Rennes team with Lyon University colleagues, well known for their experience in hepatitis virology. A friendly and confident French joint venture was established and Sylvie Rumin accepted to take up the challenging project by making the bridge between Rennes (where she got her PhD and the expertise in hepatocyte culturing), and Lyon, where she started working as postdoc scientist.

It was in 1999 that Sylvie Rumin got the piece of tumour which gave rise to the HepaRG™line a couple of years later.

According to the experimental protocol, the tumour came from a patient suffering from HCV infection and operated in Lyon for tumour ablation. She gave her consent to use the cells for research purposes, of course. Unfortunately, HCV infection markers gradually disappeared with detachment and death of normal hepatocytes surrounding the tumour and present when setting the culture, whereas only normal hepatocytes (not the transformed cells) were able to support HCV infection. Nevertheless, mixed populations of cells from the tumour remained alive.

Sylvie Rumin

Although they were negative for HCV markers, no decision to discard them was taken because (partially by chance but also thanks to extraordinary insight) Sylvie Ruminwas intrigued since the beginning by those cells present in low number and showing a morphology possibly mimicking hepatic epithelial shape. She then decided to offer vials of these cells to scientists of both teams who could have an interest in characterizing them further.

Fortunately again, one of them, Philippe Gripon, accepted to take up the challenge. His clever approach translated in an efficient selection strategy involving very hard work: in fact, the process went on for one year till he succeeded to get a high enrichment in hepatocytes.

As a reward of the major contribution provided by these 2 young scientists, I (Pr. Christiane Guillouzo) decided to use the first letter of their name to identify the cells; this is how the name HepaRG™ (for Rumin and Gripon) was created.

A period of very enthusiastic observations followed: discovering that all the liver specific functions were highly expressed by the cells, mainly those associated with detoxication metabolism and demonstrating that the cells were also able to be infected by HBV and support viral replication.

It was the first demonstration of HBV infection in an established cell line, thus strong evidence was provided that HepaRG™ cells underwent complete hepatocyte differentiation. These results were published in PNAS in 2002 together with the first description of the line. At the same time, the patenting process was initiated byINSERMwhich now covers many countries in the world.

Fortunately, in 2003 Biopredic bought the licence and immediately settled both the master and the working banks so crucial for preserving the stability of the line until today. Thanks to a wide distribution of the line, a huge number of scientific papers have originated, containing an impressive amount of data proving the performances of these cells.

It took more time for evidencing the unpredictable maintenance of hepatic progenitors, published by Parent et al in 2006, and for understanding the extraordinarly interesting biological property of transdifferentiation published by Cerec et al in 2007, which makes HepaRG™ a unique hepatic model sharing with stem cells high plasticity properties.

Finally, in 2011, conditions for getting the HepaRG™ susceptible to HCV infection were reported!

I hope that, fortunately, HepaRG™ cells have not completely disclosed all their biological secrets, mainly those related to their stemness properties, and that they will continue to thrill scientists for a long time.